ML19207B146

Submits Final Rept Re Potential Overstressing of Svc Water Sys Piping & Piping Supports During post-LOCA Conditions Due to Increased Temp Range.Summarizes Results of Piping Analysis

ML19207B146
Person / Time
Site:	North Anna
Issue date:	08/20/1979
From:	Brown S VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
656C, NUDOCS 7908230448
Download: ML19207B146 (3)

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'i' DC0 VIRGINI A EL ECTRIC AND POWrER COMP AN Y, RICNMONO. VIRGINi a 2 3M I August 20, 1979 Nr. James P. O'Reilly, Director Serial No. 656C Office of laspection & Enforcement PSE&C/CGC:adw:me U. 3. Nucicar Ragulatory Cor.raission Region II Docket No. 50-333 101 Marietta Street, Suite 3100 Atlanta, Georgia 30503

Dear Mr. O'Reilly:

Under the provisions af ICCFR50.55(e), iRC . Region II was notiftad on November 17,197d of the potential over stressing of the Service Water system piping and piping supports during post-LOCA conditions for nortn Anna i; nit 2 uae to an increased temperature range of the service water systa.t. Our Int iatarir.1 report (5N. 555d of January 26,1979) coscribed the proolem and outlined tne analytical parameters and meth-ocology to be used in solvin] it. This report will outline the specific analysas nefer aaa ana tne results of taese analyses. The scope of this effort inciauau toe krvica mer (5W) and Ccaponent CcolinJ Water (CCW)

Systems on units i anc c.

This probleu nas .>eesi addressed in two pnases.

Phase 1 was ali aaalysis of the affecte; piping in tne SW System for both units, cae unit 2 CCW Systen, and those portions of the Unit 1 CCW system which are an integral part of the 5W or unit 2 CC'.I Systems; the portions of tau CCa .<ater sys:ati analyzea in ;nasu 1 can be isolated froa chose analjzed in pnase ;, and cocmrise all cortions required for tne operation of te.it 2. This analysis incicated that one branch connec-tion in t..e servica .:cer sjs;ea r quirea acait.icnal rainforcement to caintain pi.ce stresses within allowables. A total of 427 cipe supports were reviewac,147 of wnich ravired aitner rocification to sat-isfy support allou; wies or runoval to sa .isfy ;ipe stress allowaala' .

The review of tne revised no::la leads and aquipment support loan which resulted from the pipe stress analysis in phase 1 indicated the following ucrk was required:

1. Mootfication of the pump-to-soleplate connections on each of the four SW and two auxiliary SW pumps.

2. Mooification of some ena connecticr.s on the ccmen support frame for the four CCW heat exchangers.

P00ROR5h == D 7908230

.e,..

Mr. James P. O'Reilly 2

3. Modification of the CCW piping and/or pipe supports to and from the Unit 2 reactor coolant pump (RCP) motor upper bearing oil coolers to reduce loads on four of the six cooler nozzles.

4. Modification of the CCW piping to and from the Unit 2 RCP motor air coolers to reduce loads oa all twelve cooler nozzles.

All of the physical rework required by the phase 1 analysis, as describ-ed in the above two paragraphs, has been coinplated.

Phase 2 is an analysis of the affected piping in the Unit 1 CCW system not covereu by Phase 1. The pipe stress analysis is complete and requires no moaification tc aiping. The pipe suoport analysis is complete, and of 252 succorts reviewac,114 r2 quire rework.

The review of the revised nozzla leads anc ecui.=cnt su: pert loads which rasulted frc:a the pipe stress analjsis in pnese is cetr.clete and requires no rawcrk, except for the following items:

1. The spent fuel pool coolers.

2. The Unit 1 aCP .:cter uaper tearing oil cccler nozzle loads.

3. The Unit 1 PCP r.ctor air cooler nozzle leads. - -

4. The ::oron recovery evacorator overhen ccacensers.

The engineering review to date incicates a T.inor equi;=ent support modification is required for item 1; for ite.T.s '. anc 3, todifications similar to Unit 2 are requirec; f ar it:c ;, the review to Jate indicates no re.;ork.

Witn the physical completten of all rework recuired t" ease 1, all North Anna Unit ? systems are now capa::13 ef nn?ratinc 41*.nin taeir de-sign lirits for the elevatec Service <a:3r tea peratura. Mercfore, the .

issue of service atar tercerature excursi;n sheclu ne lon:er ce a re-straint to any .:.cce af spara:. ion for norta Maa unit 2.

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Mr. James P. O'Reilly 3 We consider this to be our final report under the provisions of 10CFR50.55(e). If you have any questions, please contact this office.

Very truly yours,

! i /s. '

~

Sam'C'. Brown, Jr.

Senior Vice President-power Station Engineering and Construction ec: Mr. Victor Stallo, Director Office of Inspection & Enforcement Harold R. Denton, Director Office of lsuclear Reactor Regulation j

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